As a mother of (identical) twins, I've had to learn to tolerate the sometimes inexplicable humor my girls share.
Take yesterday, for example. We're driving down the highway, and one twin (who is wearing the same hair accessory and (almost) identical glasses as the other, which is NOT a common occurrence) says to her sister,
"You're so DUMB. Look at your dumb BOW, and your dumb GLASSES, and your dumb FACE!"
Immediately her sister ripostes, "No, YOU'RE so dumb! Look at YOUR dumb bow, and YOUR dumb glasses, and YOUR dumb face!"
Cue uproarious laughter from the girls, but not from me. I'm too busy trying not to crash the car as I simultaneously facepalm and roll my eyes.
Oh and the most inexplicable thing about all this is that my twins turn 21 this year...and they're STILL making jokes like this (and finding them funny!)